Please explain the thirty minute silence in Heaven of Revelation 8:1And when he had opened the seventh seal, there was silence in heaven about the space of half an hour.
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This verse must be considered in light of the larger passage. Let us look at that:

Revelation 8:1-6 [1] And when he had opened the seventh seal, there was silence in heaven about the space of half an hour. [2] And I saw the seven angels which stood before God; and to them were given seven trumpets. [3] And another angel came and stood at the altar, having a golden censer; and there was given unto him much incense, that he should offer it with the prayers of all saints upon the golden altar which was before the throne. [4] And the smoke of the incense, which came with the prayers of the saints, ascended up before God out of the angel's hand. [5] And the angel took the censer, and filled it with fire of the altar, and cast it into the earth: and there were voices, and thunderings, and lightnings, and an earthquake. [6] And the seven angels which had the seven trumpets prepared themselves to sound.
See All... And when he had opened the seventh seal, there was silence in heaven about the space of half an hour. And I saw the seven angels which stood before God; and to them were given seven trumpets. And another angel came and stood at the altar, having a golden censer; and there was given unto him much incense, that he should offer it with the prayers of all saints upon the golden altar which was before the throne. And the smoke of the incense, which came with the prayers of the saints, ascended up before God out of the angel's hand. And the angel took the censer, and filled it with fire of the altar, and cast it into the earth: and there were voices, and thunderings, and lightnings, and an earthquake. And the seven angels which had the seven trumpets prepared themselves to sound.

The half hour of silence occurs at the opening of the seventh and last seal. It also occurs at the beginning of the seven trumpets--another set of judgments on the earth. It is as if the seventh seal opens up into the seven trumpets. There is a distinction between the seven seals and the seven trumpets that indicates a shift in God's dealings with man in the midst of the tribulation period. The seven seals bring judgment through either manmade or seemingly natural events. They are the judgment of God, but could be dismissed as natural events. The seven trumpets, on the other hand, are clearly supernatural in cause. They are clearly the pouring out of God's wrath upon the earth. Revelation 8 describes a pause in heaven before this shift in judgment occurs. But there is more. 

An event takes places here in the heavenly temple. The Bible is clear that there is a temple in heaven. Revelation 11:19And the temple of God was opened in heaven, and there was seen in his temple the ark of his testament: and there were lightnings, and voices, and thunderings, and an earthquake, and great hail.
See All... states, "And the temple of God was opened in heaven, and there was seen in his temple the ark of his testament: and there were lightnings, and voices, and thunderings, and an earthquake, and great hail." In our passage in Revelation 8, an offering of incense is made by one of the angels. Under the law, a special offering of incense was made every morning and every evening. The offering of incense had a special typical significance. Psalm 141:2Let my prayer be set forth before thee as incense; and the lifting up of my hands as the evening sacrifice.
See All... states, "Let my prayer be set forth before thee as incense; and the lifting up of my hands as the evening sacrifice." Revelation 5:8And when he had taken the book, the four beasts and four and twenty elders fell down before the Lamb, having every one of them harps, and golden vials full of odours, which are the prayers of saints.
See All... clearly defines the type: "and golden vials full of odours, which are the prayers of saints." The incense going up was clearly a picture of the prayers of the saints going up to God.

It was when the priest Zacharias offered the offering of incense that the angel of the Lord announced to him that he would have a son whose name would be John. We know him as John the Baptist. When the priest made the offering of incense, the priest would enter the temple alone with a handful of incense in one hand and a censer with live coals from off the brasen altar in the other. The censer was a golden or brasen scoop with a handle on one end and a place for holding live coals on the other end. The coals were specifically to come from the brasen altar where animals were sacrificed because that fire had been lit by fire from God out of heaven. It was holy fire. The two older sons of Aaron, Nadab and Abihu, lost their lives when offering incense because they used strange fire--fire that did not come from God (Leviticus 10:1-2 [1] And Nadab and Abihu, the sons of Aaron, took either of them his censer, and put fire therein, and put incense thereon, and offered strange fire before the LORD, which he commanded them not. [2] And there went out fire from the LORD, and devoured them, and they died before the LORD.
See All...). This would forever bring a sense of fear and awe to the time of the offering of incense. It was a holy occasion.

When the offering of incense was made, everyone quietened down and spent time in prayer. In the story of Zacharias, "the whole multitude of the people were praying without at the time of incense" (Luke 1:10And the whole multitude of the people were praying without at the time of incense.
See All...). This explains the silence in heaven. All was quiet while God received the prayers of the saints. Also, according to Jewish tradition, the time required for the offering of incense was about half and hour. Everything fits perfectly.

There was a pause in heaven as God considered the prayers of His saints. What prayers was he hearing? Very likely, he was hearing prayers like those of the souls under the altar in Revelation 6:10And they cried with a loud voice, saying, How long, O Lord, holy and true, dost thou not judge and avenge our blood on them that dwell on the earth?
See All... - "And they cried with a loud voice, saying, How long, O Lord, holy and true, dost thou not judge and avenge our blood on them that dwell on the earth?" This cry of how long has been made by the saints through the ages. How long will it be until God judges the wickedness in this world? The answer in Revelation 8 is "No longer." As the time of silence ends, the seven trumpets began to blow and to bring their supernatural judgments on the earth. As the angel sware at the sealing of the seven thunders (at the end of the seven trumpets) in Revelation 10:6And sware by him that liveth for ever and ever, who created heaven, and the things that therein are, and the earth, and the things that therein are, and the sea, and the things which are therein, that there should be time no longer:
See All..., "that there should be time no longer." Time is up. The judgment of God comes now.